Researchers at Purdue University have created a portable refinery that converts food, paper and plastic trash into electricity. The prototype biorefinery generates approximately 90 percent more energy than it consumes.

Its efficiency owes to a series of steps:

1. Separate organic food material from residual trash, such as paper, plastic, Styrofoam and cardboard.
2. Ferment food waste into ethanol with industrial yeast.
3. Transfer non-food waste to a gasifier, where it is heated under low-oxygen conditions until it breaks down into low-grade propane gas and methane.
4. Combust gas (from non-food waste) and ethanol (from food waste) in a modified diesel engine that powers a generator to produce electricity.

Much of the process is carbon-neutral, according to Nathan Mosier, a Purdue professor of agricultural and biological engineering involved in the project. The ash output amounts to a 30 to 1 waste volume reduction.

And finally, most importantly (to the U.S. Army that is now supporting this research)–the whole apparatus could fit in a minivan.

They are not particularly concerned with whether it would be economic in your backyard. Rather if a military Forward Operating Base might be able to reduce the amount of supplies (like fuel) it needs to operate.
The high cost and danger of shipping supplies *might* justify the cost. These folks are also very interested in modules that contain photovoltaics and/or wind generators for the same reason.
It seems that at least a little bit of the money for war is going towards renewables!